1. Field of the Invention
The present invention relates to a fiber optic sensor head for detecting the shape or the distance a test object, the sensor head having an optical fiber for conducting and returning two partial beams to and from the test object and an injection/extraction lens on the test object side. The present invention further relates to an interferometric measuring system for detecting the shape or the distance of a test object, having a unit designed as a modulation interferometer and configured for generating two partial beams having an optical path length difference, and having a measuring probe and/or a reference probe.
2. Description of Related Art
Such an interferometric measuring system is described in published German patent document DE 198 08 273 by the present applicant. This and other types of interferometric measuring systems are particularly suited for interferometrically measuring rough surfaces of a measured object in the form of a test object. For this type of measuring system it has proven to be particularly advantageous that broadband radiation which is short-coherent over time may be generated by the modulation interferometer, and as it has high spatial coherence at the same time, may be used for heterodyne interferometric measurement of a rough surface. In the above-referenced patent application, a similar measuring probe for the interferometric measuring system is provided with a measuring branch and a measuring reference branch as well as a beam splitter, and is designed as a Michelson or Mireau interferometer. The optical path difference generated in the measuring branch and in the measuring reference branch is compensated for using a delay element.
These types of interferometric measuring systems not only have proven to be advantageous compared to mechanical sensors, which as a result of the necessary surface contact may damage sensitive surfaces, but also have the advantages described in the above-referenced patent application with regard to the possibility for using broadband radiation which is short-coherent over time.
However, the Michelson or Mireau interferometers for the measuring probe and/or reference probe provided in the cited patent application have proven to be comparatively space-consuming, since the measuring branch and the measuring reference branch must be situated transversely to one another.
A measuring probe, having a different design in this respect, for use with a modulation interferometer is disclosed in published German patent document DE 198 19 762, but is still in need of improvement.